Si3N4 films have been deposited on silicon substrates at high temperatures (800–1000° C) in a plasma CVD hot wall reactor using SiF4 and NH3 as primary reactant gases. In this range of temperatures the activation energy is 35.9 Kcal mol−1 grad−1. The effect of an RF plasma induced either in the up or in the down stream configuration has been evaluated. The results show that in the 200–400 w range the reaction rate increases linearly with the RF power. The addition of hydrogen to the above gas mixture also produces an enhancement of the deposition reaction, probably as a consequence of the inhibition of the etching effect of the fluorine atoms on the Si3N4 deposited layers.